Back-up Plan
by biawutnow
Summary: Because even the nicest girls can do the naughtiest things.


**A/N: **So_ this is my first Adventure Time story, and it's complete and total smut. I don't know what to say, other than I hope you like it, and that I hope I didn't make Marshall Lee seem too creepy, haha. Enjoy, please review if you can!_

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Marshall Lee was dissatisfied. More so than he had been in a long time. As he idly floated in the air and ghosted his fingers over the strings of his guitar, he found himself unable to keep his thoughts from drifting back to the source of his frustration. Fionna.

The girl had proven to be more of a challenge than he had originally anticipated. Even HE wasn't sure how he felt about her. Was she just another fickle plaything to toy with? Or did he have a legitimate interest in her? How did she even feel about him? He certainly felt possessive of her. There was nothing more irksome to him than her abrupt departures to babysit the helpless prince gumball.

Rather suddenly, Marshall forced himself to stop strumming his instrument and land on the floor of his bedroom. It wasn't like him to mope in such a manner. If he felt strongly about something, then he would hatch a plan to address those feelings. Acting on impulse was just how he went about things.

So, after a few minutes of scheming and preparation, he set out from his home, determined to return with results.

* * *

The storm that raged outside Fionna and Cake's place had taken them both by surprise. Considering how pleasant the weather had been earlier that day, the rain and thunder were completely out of the ordinary.

"Girl, this weather is making my fur crawl" Cake complained to her companion. Aside from Cake's aversion to water, she was also terrified of thunder.

"I'm sorry Cake...here, take this" Fionna offered, holding out a pair of ear buds. "Why don't you go lay down? I'll be up there in a little while."

Cake gratefully accepted the ear buds from Fionna, and headed in the direction of their bedroom. Fionna returned to the kitchen, where she had been going through an old cookbook, picking out recipes to try.

After sitting at the table for a few minutes, she heard someone banging loudly on the front door. She jumped from her chair and ran to answer the knocking, certain that it was the prince calling upon her at such a late hour.

Her guess at her guest was incorrect, however. Instead of Prince Gumball, it was Marshall Lee who stood on her doorstep, his eyes wide and frantic. "Fionna, I need you to come quickly. Something awful has happened."

"Marshall? What's going on? Do I need to get Cake?" Fionna asked, taking a few steps back.

"There's no time for that, just come with me!" Marshall cried, grabbing her hand and dragging her through the door.

Fionna held on to Marshall tightly as he shifted into his demon form, the rain soaking her thoroughly as they flew through the air. His wings beat furiously against the storm, and Fionna was forced to concentrate more on keeping her grip rather than paying attention to where they were going.

After several tense moments, the two of them landed in front of Marshal Lee's home, and he abruptly shifted back into his human form. His hand remained tightly clamped over hers as he rushed through the front door, the urgency in his movements keeping Fionna from asking any questions. Until-

Marshall Lee disappeared, leaving Fionna alone in the dark, large living room. She heard a slam, and turned around just in time to see Marshall Lee closing and locking the front door, a wicked smile on his face.

"Marshall..." Fionna called shakily, unease welling up in her stomach. "What's going on?"

"Oh, nothing. I just wanted to spend some time with you." He admitted, his tone light and easygoing.

"You mean...you dragged me out here in the middle of the night for _nothing_?" She asked, the unease slowly turning into anger.

"Yeah, got a problem with that? I thought you liked hanging out with me" he teased, the smile still on his face as he walked towards her.

"I do like hanging out with you, but can't you just ask me to like a normal person? I'm completely soaked now, it's the middle of the night, and Cake's probably frightened!" Fionna yelled, making no effort to conceal the irritation in her voice. Her frustration with the vampire king's antics had finally hit a boiling point, and she wasn't afraid to show it.

Marshall stood in front of her now, his grin beginning to falter. "If you're concerned about being wet, just take your clothes off. You're acting more whiny than gumball" he complained. Before Fionna had time to respond, he reached out and removed the bunny hood from her head, tossing the soaked cap to the floor.

"Marshall, you're being a total jerk!" Fionna complained, her hands flying to her hair in an attempt to cover the tangled mess. "Why are you acting like this?"

"Maybe you should just come to accept the fact that I am a jerk. Oh, and you can stop acting like you dislike me now, it's not like Cake is around to watch you."

Fionna suddenly felt indignant, and she made to smack Marshall's arm, but he caught her wrist before it made contact.

"Marshall, let me go. I want to go home." Fionna commanded, her cheeks red and her skin flushed.

"Well, _I _want you to stay. So I think that's what's going to happen" Marshall responded, grabbing a hold of her other wrist. Fionna struggled in his grasp, and he let out a deep laugh as he roughly pushed her against a wall.

"I warned you so many times that I was a bad boy, and you just didn't listen..." He cooed, his grip remaining firm on her wrists as he lowered his lips to her neck.

"Marshall, please..." Fionna cried, the anger ebbing away as an unfamiliar warmth swept through her body.

"Please what? I know you don't want me to stop. I've told you that I can see through you, Fionna...and I know you want me..."

Even as he uttered those words, Marshall wasn't so sure. This whole scenario had stemmed from his uncertainty regarding her feelings, and so far his antics hadn't given him the response he wanted.

"Marshall, I just can't..."

"And why not?" He growled, his lips barely grazing the skin on her neck as he spoke.

"Because, I've just...I've never felt this way about someone before. I'm confused, I don't know what to do. I've never...been with a boy"

She choked over the last part awkwardly, embarrassment overcoming her.

"You mean...you're a virgin?" Marshall asked, suddenly drawing himself back in disbelief. He released her wrists and stepped away from her. She folded her arms across her chest defensively, a frown on her lips and her voice quavering.

"Yes. I thought you knew that."

"No, I had no idea." He stated honestly, the surprise evident on his face.

_'I'm a jackass. This whole time I thought we were playing cat and mouse, when really...'_

Marshall turned from her in attempt to hide his guilt from her.

"I'll take you home, Fionna. I'm sorry for tonight. I know I'd be asking a lot if I requested that you pretend tonight never happened, but..."

"Marshall, wait" Fionna called, suddenly grabbing his arm.

"I don't want to leave. Please, let me stay"

Marshall glanced over his shoulder at her. Fionna's cheeks were still flushed, but she looked determined.

"Are you sure about that? There's no going back if you tell me yes."

"I'm sure."

The mischievous grin from earlier found it's way back on his lips.

"Well then, follow me, Fionna. I'm going to give you a lesson that no one else could ever teach you."

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That's it for now, I'll try to update soon! Please leave a review


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